RJSkywalker

Hey guys,

 

 I had a question regarding 2 line segments. Say we have 2 line segments whose origin and lengths are given as: (P0, L0) and (P1, L1) respectively. I need to find when can they end at the same point. The line segments lie anywhere in 3D space.

 

One of the approaches I could think about is: Let's say this common end point is T and the points are A and B. So for the line segments with A and B as origins, A,B and T must form a triangle. Length of vector AT = L0 and length of vector BT = L1. But since the orientation of the line segment is not known, there can be a lot of possibilities. Lets say we choose a particular orientation for line segment AT as (i,j,k) - 1st octant. So now we can move anywhere in space  from T but only by a distance L1 to find BT. 

 

This is where I m not sure how to move forward. 

Hi people,

I have a runtime DEBUG Assertion error when I m trying to setup a basic application using the latest Nvidia PhysX 3.2 sdk. I was just using the documentation and the tutorial mentioned at this blog : http://mmmovania.blo...th-physx-3.html as the only guide. He does mention a small change required for the 3.2 sdk.

This is where I m getting the assertion:

gPhysxFoundation = PxCreateFoundation(PX_PHYSICS_VERSION, gDefaultAllocatorCallback, gDefaultErrorCallback);

The declarations are:

PxFoundation* gPhysxFoundation = NULL;
static PxDefaultErrorCallback gDefaultErrorCallback;
static PxDefaultAllocator gDefaultAllocatorCallback;

And the Assertion is : Expression: (reinterpret_cast<size_t>(ptr) & 15) == 0 in the file: \include\extensions\pxdefaultallocator.h
Now according to the documentation, PhysX does implement a default version of the Default Allocator class and for the windows platform it does call _aligned_malloc(size, 16). Because this is what is happening. Its not able to align it to 16 bits.

Does anyone know how to solve this issue? I m only starting to learn PhysX and I cannot move forward without solving this issue.

Hey people, I am trying to implement a basic raytracer application. I m not using in graphics library. Just making use of the fundamental concepts.
I m having a problem while displaying my image. Its a simple utah teapot.

This is how I am implementing my ray tracing. I m not considering shadows and secondary rays yet until I get the teapot rendered.

1. Constructing the ray through the center of the pixel. Given: camera position, lookat, up vector, camera FOV. All of them are in world space.
- I m using the ray equation r = origin + t*direction
origin is my camera position. I find the 3 camera axes u,v,w:
w = lookat - camposition; u = crossproduct(w,camera->up); v = crossproduct(u,w); Normalize u, v, w
I m choosing distance to the image plane, d = -5
I m using my image plane as : left = -4, right = 4, top = 3, bottom = -3
using this i m calculating the pixelPositions: x = left + (right-left) * (i+0.5) / screenX; y = bottom + (top-bottom) * (j+0.5)/screenY
i,j is the i,j the pixel
So I get the ray direction = pixelScreenPosition - Origin
= xU + yV - d*W
I normalize this.
This completes this function

2. Before performing the intersection, i do the transformation. I m using the triangle primitives. All the vertices are in Model Space and even the Vertex Normals. So I convert them to world space.
3. Then I do the intersection of the ray with the triangle and return the closest point.
4. Then I perform the shading calculations.

I m not sure about the ray construction step. I could include the code. I hope the theory is right

Hey people,

I have a maze and some agents moving through it using A star search. I'm using GLUT to do the rendering. After completing the path the agent returns to its original position and the cycle continues. The problem is in the render loop:
if the number of agents = 2, at first the 2nd agent gets rendered, then it kind of vanishes so that only 1 agent is shown. This agent completes the path and then when it restarts from its original position, agent 2 shows up and then both of them move. Even when I increase the number of agents to more than 2, initially all of them show up and then not more than 2 agents are shown at a time. Here's my code:

This is the main render loop:

static void render(void)
{
  glLoadIdentity();
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// gluLookAt(-20.0f,5.0f,0.0f,-20.0+cos(270.0),5.0f,0.0+sin(270.0f),0.0,1.0,0.0);

  glPushMatrix();
   glLoadIdentity();
   //glTranslatef(-27,-10,-85);    //setting the appropriate camera look at (do it in a separate function)
   //glRotatef(-90.0,1,0,0);        
    renderScene(-27,-10,-85);
    renderAgent();
  glPopMatrix();
    
// glDrawPixels(DIM,DIM,GL_RGBA,GL_UNSIGNED_BYTE,0);
  glutSwapBuffers();   //swaps the front and back buffers
}

Render scene is:
void renderScene(float x, float y, float z)
{

    glPushMatrix();
        glLoadIdentity();
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glColor3f(1.0f,1.0f,1.0f);
        glTranslatef(x,y,z);
        glRotatef(-90.0, 1, 0, 0);
        pMaze->displayMaze();
   glPopMatrix();
}

My update function: I m using glTimer:

void updateScreen(int value)
{
    moveAgent();
    glutPostRedisplay();
    glutTimerFunc(500,updateScreen,0);
}

and this is the move agent function:
void moveAgent()
{
    for(int i = 0; i < numRows; i++)
    {
        //reset the current position of the agent and then move it
        int a = pAgents[i].Position.x;
        int b = pAgents[i].Position.y;
        pMaze->m_Maze[b][a].setCellValue(UNOCCUPIED);
        
        pAgents[i].positionIndex++;

        if(pAgents[i].positionIndex >= pAgents[i].PathInMaze.size())
            pAgents[i].positionIndex = 0;

        pAgents[i].Position.x = pAgents[i].PathInMaze.at(pAgents[i].positionIndex).getCellX();
        pAgents[i].Position.y = pAgents[i].PathInMaze.at(pAgents[i].positionIndex).getCellY();
    
        a = pAgents[i].Position.x;
        b = pAgents[i].Position.y;
        pMaze->m_Maze[b][a].setCellValue(OCCUPIED);
        
    }
}

Here is the renderAgent function:
void renderAgent()
{

    for(int i = 0; i < numRows; i++)
    {
        float x1,z1;

        x1 = -3.75 + ((float)pAgents[i].Position.x * 2.50f);
        z1 = -9.0 + 1.25 + 2.50f + ((float)pAgents[i].Position.y * 2.50f);

        glPushMatrix();

            glColor3f(1.0f,0.0f,1.0f);
            glTranslatef(-27,-10,-85);
            glRotatef(-90.0, 1,0,0);
            // glScalef(0.5,0.5,0.5);

            glBegin(GL_QUADS);
                glVertex3f((x1 + 0.25f) , 0, (z1 - 1.25f));
                glVertex3f((x1 - 0.25f) , 0 , (z1 - 1.25f));
                glVertex3f((x1 - 0.25f) , 0 , (z1 + 1.25f));
                glVertex3f((x1 + 0.25f) , 0 , (z1 + 1.25f));
            glEnd();
            // Bottom


            glBegin(GL_QUADS);
                glVertex3f((x1+0.25)  ,-0,  (z1+1.25)); // Top Right Of The Quad (Bottom)
                glVertex3f((x1-0.25)  ,-0, (z1+1.25)); // Top Left Of The Quad (Bottom)
                glVertex3f((x1-0.25) ,-0,  (z1-1.25)); // Bottom Left Of The Quad (Bottom)
                glVertex3f((x1+0.25) ,-0,  (z1-1.25)); // Bottom Right Of The Quad (Bottom)
            glEnd();
            // Front

            glBegin(GL_QUADS);
                glVertex3f((x1+0.25), 0, (z1+1.25)); // Top Right Of The Quad (Front)
                glVertex3f((x1-0.25), 0, (z1+1.25)); // Top Left Of The Quad (Front)
                glVertex3f((x1-0.25),-0, (z1+1.25)); // Bottom Left Of The Quad (Front)
                glVertex3f((x1+0.25),-0, (z1+1.25)); // Bottom Right Of The Quad (Front)
            glEnd();
            // Back

            glBegin(GL_QUADS);
                glVertex3f((x1-0.25),0,(z1-1.25)); // Top Right Of The Quad (Back)
                glVertex3f((x1+0.25),0,(z1-1.25)); // Top Left Of The Quad (Back)
                glVertex3f((x1+0.25),-0,(z1-1.25)); // Bottom Left Of The Quad (Back)
                glVertex3f((x1-0.25),-0,(z1-1.25)); // Bottom Right Of The Quad (Back)
            glEnd();
            // left of cube

            glBegin(GL_QUADS);
                glVertex3f((x1-0.25), 0,(z1+1.25)); // Top Right Of The Quad (Left)
                glVertex3f((x1-0.25), 0,(z1-1.25)); // Top Left Of The Quad (Left)
                glVertex3f((x1-0.25),-0,(z1-1.25)); // Bottom Left Of The Quad (Left)
                glVertex3f((x1-0.25),-0,(z1+1.25)); // Bottom Right Of The Quad (Left)
            glEnd();
            // Right of cube

            glBegin(GL_QUADS);
                glVertex3f((x1+0.25), 0,(z1-1.25)); // Top Right Of The Quad (Right)
                glVertex3f((x1+0.25), 0,(z1+1.25)); // Top Left Of The Quad (Right)
                glVertex3f((x1+0.25),-0,(z1+1.25)); // Bottom Left Of The Quad (Right)
                glVertex3f((x1+0.25),-0,(z1-1.25)); // Bottom Right Of The Quad (Right)
            glEnd();
            glPopMatrix();
        
    }
}

So I m not sure why they get rendered only 2 at a time. If anyone can point out what is going wrong, I would be appreciate it